1. Field of the Invention
This invention relates to a compressible bobbin for yarn treatment which, in performing yarn treatment such as dyeing, enables the avoidance of yarn biting in the bobbin and to make the compression degree thereof uniform, thereby attaining a smooth and even treatment.
2. Statement of Related Art
In general, cheese dyeing has been carried out by winding up yarns on tapered or cylindrical bobbins to make yarn cheeses and mounting the cheeses onto each spindle to stack them one upon another while interposing a spacer between cheeses.
However, the occurrence of variation in density of the yarns was unavoidable owing to the dispersion in tension applied when yarns are wound up, or other causes. The variation in density of yarns was seen not only among cheeses, but also in each individual cheese, which was a major cause of uneven dyeing.
In order to eliminate uneven dyeing and to achieve uniform dyeing, attempts have been made to compress the cheeses after winding-up in the axial direction thereby making the yarn density uniform, and accordingly, many bobbins and methods have been proposed. Such examples include a compressible bobbin that has a number of passage holes for a treating liquid round its outer periphery and is compressible in the axial direction; an improved compressible bobbin over the aforementioned bobbin that is constructed to have a greater contraction ability in its intermediate portion as compared with both end portions in view of the fact that with a compressible bobbin contractile evenly in every portion, both end portions thereof collapse earlier than the intermediate portion; in case where bobbins are compressed in a multi-tier stacked state, a method for regulating the compression degree of the stacked bobbins to a definite magnitude by interposing incompressible bobbins between compressible bobbins belonging to the intermediate tiers thereby attaining a uniform compression in view of the fact that otherwise, the compressive degree of the intermediate-tier bobbins is lowered.
However, problems with the compressible bobbins stated above are that when wound-up bobbins are compressed, there is no stopper means for regulating the compression degree of the bobbin and consequently, unevenness in compression is liable to occur; and the inner yarns are, when compressed, bitten between annular horizontal frames of the aforesaid bobbins and are subjected to yarn treatment in the yarn biting state, which have impeded a smooth, uniform treatment of yarns.